1. Field of the Invention
The present invention relates to the field of motorized solar protection elements and in particular of awnings with arms, such as for example terrace awnings.
2. Brief Description of the Related Art
Existing installations of motorized awnings include an awning cloth and arms that can unfold for guidance of the cloth whose movement accompanies a movement for deployment or retraction of the cloth, the cloth being capable of being rolled around a tube set in motion by an actuator.
More precisely, an awning installation with arms usually comprises the following elements: a rolling tube, held at its ends in a case or by supports, foldable arms, an awning cloth and a rigid bar called a load bar. A tubular actuator makes it possible to motorize the installation.
The awning cloth is attached by one of its sides to the rolling tube inside which the tubular, actuator is located. This actuator rotates the tube and consequently makes it possible to roll up or unroll the cloth. The cloth is also attached on its opposite side to said load bar. The latter makes it possible to hold the cloth and, where necessary, is used to close the awning case when the cloth is in its retracted position.
The awning arms are attached on the one hand to the awning case (or to appropriate supports) and on the other hand to the load bar. They have at least one articulated elbow allowing them to fold or unfold. The arms are furnished, usually at the elbow, with springs that are tensed when the cloth is retracted.
Awnings with arms are usually deployed substantially horizontally. Thus, the cloth cannot be deployed only under the effect of the weight of the load bar. For deployment, the arms have a tendency, under the effect of the springs, to try to unfold. Accordingly, if the actuator releases the rotation of the rolling tube, the cloth is operated by the arms and the awning deploys.
When the awning is retracted, the actuator rotates the rolling tube which has the effect of pulling on the arms via the cloth to fold them.
The springs of the arms usually have a strong stiffness factor. Specifically, it is required that the awnings conventionally sold on the market are unrolled with the cloth under great tension, irrespective of the stopping position, for esthetic and technical reasons (no water pocket in the event of rain, more rigid holding and hence resistance to the wind, etc.).
These cloth tension stresses cause over time a distention and lengthening of the latter which may lead to carrying out readjustments.
The fully deployed position, also known as the “bottom end-of-travel position” is identified without abutment, usually thanks to a metering device. In the existing installations, this position also corresponds to a locking position in which the arms are unfolded beyond a position in which the segments of the arms are aligned. More precisely, in existing installations, each arm comprises at least two segments articulated relative to one another about an axis of rotation perpendicular to the plane of movement. An angle α is defined by the two segments in the plane of movement. This angle α increases as the cloth is deployed. The locking position corresponds to a position in which the angle α is greater than 180°. In this position, it is said that the arms are “braced”. This locking position allows a good retention of the tension of the cloth, particularly relative to the wind.
On the other hand, the passing of this locking position, during the deployment or more particularly the retraction of the cloth, requires the actuator to be capable of developing a high operating torque.
Accordingly, the actuators designed for awnings with arms are dimensioned for a high torque that is globally necessary only for unlocking the arms, that is to say the transition from the locking position. The rest of the travel requires only a medium torque.
In addition, the whole awning must satisfy criteria of precision, sensitivity and sealing.
Because of these criteria, the motorization of the awnings is costly since the actuators must be powerful (from 25 to 120 Nm) and the metering devices elaborate.